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From: Pietro Gagliardi <pietro10@mac.com>
Subject: Re: [9fans] How to move to rc from sh/bash
Date: Sun, 10 Feb 2008 12:16:50 -0500
To: Fans of the OS Plan 9 from Bell Labs <9fans@cse.psu.edu>
Topicbox-Message-UUID: 4ec324e8-ead3-11e9-9d60-3106f5b1d025

On Feb 10, 2008, at 11:59 AM, Gorka Guardiola wrote:

> On Feb 9, 2008 8:53 AM, Hongzheng Wang <wanghz@gmail.com> wrote:
>> Hi all,
>>
>> 2. In non-interactive use (script programming), what's the main
>> advantages of rc over sh/bash?
>
> Things I like of rc:
>
> In both interactive and non-interactive, spaces do not bite you in rc.
>
> in bash
>
> if [ $bla -eq $otherbla ] ; fi endif... ahhh, I can=B4t remember the
> syntax and get the spaces wrong,

The proper is

if [ $bla -eq $otherbla ]; then
	:
fi

The advantage of rc is that that : is not necessary!

Oh, and let's not forget what happens when bla or otherbla is nil! In =20=

rc,
	if (~ $bla $otherbla) { }
is all that is needed - no hooks.
>
> Someone else said it, only one quoting simbol
> (what does " bla \$e'o" do on bash?, I just invented it, but every =20
> time I see
> double qoutes I start trembling)

It produces the string ' bla$e''o' in rc syntax. The one thing I like =20=

about two quoting styles  in the Bourne shell is that I can use =20
escape sequences. The one thing I dislike about bash is that bash =20
fucks up this quote system.
>

And here is my 2 cents:

- List objects are STANDARD (bash/kornshell arrays are not)
	x=3D(a b c)
- The seq statement is standard
	for (i in `{seq 1 10}) echo $i
- Removable functions
	fn x { echo 4 }
	fn x
	x=3D4
- >[] piping syntax is much more intuitive
- |[2] to pipe arbitrary file descriptors. One time, to skim through =20
errors from gcc to find out if I had mistyped a member of a struct, I =20=

had to do
	gcc a_file_in_my_os.c 2>&1 | grep member
   In rc:
	8c a_file_in_my_os.c |[2] grep member
- Empty condition bodies! while(){echo y} is the yes command. It's =20
much more terse.
- aux/getflags is faster than while getopt (no loop involved)
	My next plan is to rewrite all of /rc/bin to use aux/getflags. =
Any =20
objections?
- The trap statement is gone - goodbye confusing hooks and no way of =20
telling signal 1 from a command/function called 1
	Instead, you define functions sigterm and sigkill (I think)

And what I dislike:
- >[2=3D] is not the same as >[2]/dev/null (some programs crash with =20
the former